Hazelcast:添加索引时出现问题 [英] Hazelcast: Issue while adding index

问题描述

我有一个hazelcast实例，其键的类型为MyObject，值是一个枚举. 假设MyObject类的属性之一是date，其类型为java.sql.Date.

I have a hazelcast instance whose key is of type MyObject and value is an enum. Let's say one of the attributes of MyObject class is date which is of type java.sql.Date.

    class MyObject {
       private Date date;
       public Date getDate() {
         return date;
       }
       public void setDate(Date date) {
         this.date = date
       }
    }

public enum MyEnum {
  TEST_ENUM;
}

我还使用谓词对键进行过滤以检索枚举值. 例如:

Also I am using predicate to filter on the keys retrieve the enum value. For ex:

EntryObject entryObject = new PredicateBuilder().getEntryObject();    
PredicateBuiler predicateBuilder = entryObject.key.get(date).isNull;

这是我尝试添加索引的方式:

This is how I am trying to add index:

IMap<MyObject, MyEnum> map = hazelcastInstance.getMap("test");    
map.addIndex("date", true)

但是一旦执行，就会引发异常:

But as soon as this gets executed an exception is being thrown:

com.hazelcast.query.QueryException: java.lang.IllegalArgumentException: There is no suitable accessor for 'date' on class 'class com.main.constants.myEnum'
at com.hazelcast.query.impl.getters.ReflectionHelper.createGetter(ReflectionHelper.java:176)
at com.hazelcast.query.impl.getters.Extractors.instantiateGetter(Extractors.java:88)
at com.hazelcast.query.impl.getters.Extractors.getGetter(Extractors.java:73)
at com.hazelcast.query.impl.getters.Extractors.extract(Extractors.java:57)
at com.hazelcast.query.impl.QueryableEntry.extractAttributeValueFromTargetObject(QueryableEntry.java:156)
at com.hazelcast.query.impl.QueryableEntry.extractAttributeValue(QueryableEntry.java:82)
at com.hazelcast.query.impl.QueryableEntry.getAttributeValue(QueryableEntry.java:48)
at com.hazelcast.query.impl.QueryableEntry.getConverter(QueryableEntry.java:67)
at com.hazelcast.query.impl.IndexImpl.saveEntryIndex(IndexImpl.java:67)
at com.hazelcast.map.impl.operation.AddIndexOperation.run(AddIndexOperation.java:75)

我了解它正在尝试在值类中找到索引属性

I understand it's trying to find the index attribute in the value class

如何使此功能正常工作，即在键上而不是在值上添加索引.

How do I get this thing working i.e. add the index on the Key rather than on the value.

推荐答案

在编写测试时，我实际上发现了您的问题:-)

While writing a test I actually found your problem :-)

import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.IMap;
import com.hazelcast.query.EntryObject;
import com.hazelcast.query.PredicateBuilder;

import java.io.Serializable;
import java.sql.Date;

public class Test
{
    public static void main(String[] args)
    {
        HazelcastInstance hz = Hazelcast.newHazelcastInstance();

        IMap<MyObject, MyEnum> map = hz.getMap("test");

        EntryObject entryObject = new PredicateBuilder().getEntryObject();
        PredicateBuilder builder = entryObject.key().get("date").isNull();

        map.addIndex("__key#date", true);

        map.put(new MyObject(), MyEnum.TEST_ENUM);
    }

    public static class MyObject implements Serializable
    {
        private Date date;

        public Date getDate()
        {
            return date;
        }

        public void setDate(Date date)
        {
            this.date = date;
        }
    }

    public static enum MyEnum {
        TEST_ENUM;
    }
}

诀窍是基于map键而不是默认值创建索引.您已经在查询entryObject.key()中进行了此操作，但是在索引定义__key.date中未进行此操作.

The trick is to create the index based on the map-key and not the value which is taken by default. You already did it in your query entryObject.key() but missed it on the index definition __key.date.

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